From one of our fellow bloggers, Kean Walmsley, and a very interesting article on the 'cloud':

This is a topic I’ve been meaning to cover for some time. It concerns a transition we’re seeing overall in the software industry, and is certainly one that the ADN team broached in depth during the last two DevDays tours.

I don’t think anyone is in real doubt, at this stage, that software is increasingly being delivered “as a service”, rather than via locally-installed desktop applications. Some readers may understandably be skeptical about the near-term likelihood of powerful design tools working in the cloud… I personally believe it’s an inevitable shift (whether we’re talking about a timeframe of 2 years or 10 is the real the question, in my mind), but I won’t try to convince anyone of the correctness of these opinions....

Install Optimization first THEN go to the Environment tab to run Optimization.

When you open Optimization from Inventor, you will be prompted for your Subscription center username and password.

Thanks to Bob Vander Donck, the Inventor Team and Byron Morales for this workaround.

Epilogue

This issue should be solved in Inventor 2012 SP1.

If you are a PrDS user, the Optimization patch will be downloaded automatically once you launch Inventor, the downloading location is in the folder " %Temp%", the time of the downloading depends on your network speed, when the downloading is finished a automatic prompt message dialog will be shown in Inventor, and Optimization patch is named "centaurupdate.exe" will be in folder " %Temp%".